Thanks for stopping by. This is a tough one because appraisals are such integral parts of a real estate transaction and yet what you are really paying for is one persons educated (ostensibly VERY educated :-) opinion but the truth of the matter is that you don't really find out what true market value is until the property is put forth on the open market and the ready, willing a able buyer's tell you via their offer, or lack of offer, what they are willing to pay.
As for the appraisal you already received, you can contact the appraiser and ask for justification on the result and if you really believe that things are seriously out of whack, there is a mechanism in place to lodge a complaint. I don't have that info at my fingertips but if you need it, I can see about getting it for you.
That being said, looking at the situation from the other side of the coin, if the properties that were used to comp your home are in your immediate area then they are indeed impacting the value of your home. This is another reason why when a home goes into Foreclosure and is vacated it is so critically important for it to be maintained and for it to find another family to live in it and love it as quickly as possible.
Houses are really a bit like apples and when one goes bad the others nearest it are now several steps closer to following in its footsteps and "going bad" (so to speak) too.
You say that you are selling your home, have you already listed your home with an agent and if so, what did the CMA (Comparative Market Analysis) that the agent should have done for you as part of their listing presentation indicate? A good agent should have their finger on the pulse of the current market, should also know what factors are influencing value there and should also be familiar with how different neighborhoods are potentially viewed by the buyer.
They are not appraisers (nor am I) and their opinion should not be and can not be used in place of that of a qualified appraiser, but if the appraiser in question is not experienced and is not also a local expert then problems can arise.
One thing you might be able to do in future, to try to help ensure (not guarantee...) that you don't have this happen when the appraisal is being done for the potential buyer's lender is to have your agent pull comparable properties for your home to provide to an appraiser who may very well be from outside, and in most cases well outside the area (especially now owing to the ruling about appraiser's having to be chosen based upon their management company alone and not their knowledge or experience) with the data that they will need to get a more accurate picture of your homes value as it stacks up apples-to-apples against the others it should be compared against.
I hope that helped. If you have any additional questions, or need any further information, please don't hesitate to ask!
Take care and have a wonderful day!
Tisza Major-Posner, Realtor, SFR*, RREOBS** DRE#01784679, IVPG Realty (909) 837-8922
* National Association of Realtors Certified Short Sale and Foreclosure Resource Specialist
** California Association of Realtors Certified Residential REO Buyer Specialist